Bests & Worsts Reviews from Amazon

I purchased this book thinking that it would be as well-researched and written as his previous two works, "The Tipping Point" and "Blink." Less than a third of a way through the book, however, I began to become concerned that Gladwell's enthusiasm for his topic had blurred his view of important related factors. As a statistician, I was troubled by his apparent lack of understanding of the concept of "range restriction" in correlational research. He notes that IQ and success appear to be fairly well correlated up to an IQ of 120 or so, and that beyond this level there is very little relationship between IQ and success. Only 10% of the population has an IQ above 120, meaning that very few fall into this classification. Past an IQ of 132, less than 2% of the population is found. It is clear that one cannot correlate a constant with a variable, since the constant does not change no matter what the value of the variable. Narrowing down the IQ scale to only persons above 120 makes the IQ scale close to a constant. To provide an analogy, consider the correlation between height and basketball ability. Up to a height of about six feet two inches, there is a very high correlation between height and basketball ability. Above that height, however, other factors become more important than height. Agility, good ball-handling skills, eye-hand coordination, etc., all trump height as important facets of a good basketball player among the tallest 10% of the population. A clumsy seven-footer will never be able to compete with a skilled six-foot-two player. All of this does not prove that height is unimportant in basketball (even among the top 10% of the population in height), but just that by restricting the range of basketball players to those over six-foot-two essentially guarantees that the correlation of height with basketball skill will be low. Another sloppy statement in the book indicates that the 1918 flu pandemic was followed by "the First World War, then the Depression, then the Second World War," where clearly the First World War preceded the flu pandemic. Although there is much about the book that is interesting, these two missteps alone reveal a lack of attention to detail that leads one to wonder how valid the rest of the book is. I sincerely hope that Gladwell's next book will be more along the lines of "The Tipping Point" and "Blink."